The prevention of fractures in the aged population is largely focused on pharmacologic interventions that inhibit bone resorption. The need for non-pharmacologic approaches to improve the musculoskeletal system as a whole and ultimately reduce the risk for fracture, forms the basis for this competing continuation of our ongoing randomized, double-blind, placebo-controlled trial of low magnitude mechanical stimulation (LMMS) called the "VIBES" trial. This trial, initiated in 2007 to study the skeletal effects of LMMS, has randomized 174 of the originally targeted 200 elderly participants with an adherence rate of 80%. In this continuation, we propose to extend the study intervention and follow up by one additional year, and to expand the scope of the science by considering a broader range of measures relevant to musculoskeletal health, including muscle area, density, and strength, as well as postural stability. This will also increase our power for the primary skeletal outcomes, which will be only 41% if the trial does not continue one additional year. The DSMB for the trial has recommended not unblinding any aspect of the current study, and is supportive of the extension to the VIBES trial. The overarching hypothesis of this clinical trial is that LMMS will have favorable effects on bone, muscle, and postural stability in a sample of independently living seniors. Thus the first aim of the project is to determine the skeletal effects of LMMS over a three year period by assessing serial quantitative computed tomography (QCT) measures of volumetric trabecular bone mineral density (vTBMB) of the hip and spine in the elderly subjects already enrolled in the original two-year study. During the trial we have developed novel methods of examining our QCT scans of the hip for muscle area and density, and have been collecting other measures not originally included in the trial, namely, muscle strength of the lower extremity, and postural stability using a balance platform. This provides data upon which the second aim is based. We hypothesize that LMMS will result in improved muscle area, density and strength, and will improve balance. The ongoing trial is well established in the senior communities, the study team has a successful track record, and there have been no safety concerns to date. Thus there is now a window of opportunity to continue the trial for an additional year and test multiple hypotheses surrounding this unique non-pharmacologic intervention. PUBLIC HEALTH RELEVANCE: The prevention of fractures in the aged population are largely focused on drug therapy to inhibit bone loss. This clinical trial of low magnitude mechanical stimulation (LMMS) in 174 elderly subjects residing in 16 retirement communities around Boston, MA (using 0.3g @ 30Hz, 10 min/d of LMMS) is intended to test a multidimensional, non-drug approach to improving the musculoskeletal system as a whole (bone, muscle, and balance). The significance of the study is that it will test the efficacy of this unique intervention to improve multiple components of the musculoskeletal system that contribute to fracture risk.